All very nice, none of it true. That is to say, none of these trite nicknames have any provenance in the men who wrote these works. Here are three reasons that I wish we'd stop using them:

It's a kind of sleight of hand—false advertising, if you prefer—presented to an unwitting, but happily complicit, public. Whether bestowed by ingenious publishers seeking to maximize profits, influential critics whose words were swallowed whole as the gospel truth, or indolent listeners utilizing expedient shorthand, these names have served to coarsen artistic sensibilities by reducing an entire cosmos to an easily digestible syllable or two: the original "sound-bite", preceding the television age by a comfortable century. Think no further than the "Moonlight"—a name that has forever tarnished with false sentimentality that paragon of high feeling, and one that is, moreover, stunningly unsuited to the last two movements of the sonata.

Then there is the absurd randomness that defies logic and offends reason: Why do we persist with the "Waldstein" Sonata (a dedication not considered to be especially meaningful for Beethoven), but not, say, the "Sonnenfels" Sonata (Op. 28) or the "Ertmann" Sonata (Op. 101)?